1. Field of the Invention
The present invention relates to hearing aids. As used throughout this application including its appended claims, a “hearing aid” is a device having an input for providing a sound signal representing a sound to be heard by a user, a processor for processing the sound signal so as to compensate for a hearing impairment of the user, and a speaker for reproducing the compensated sound into the ear of the user. The invention, more particularly, relates to a hearing aid to fit into or to be worn behind the wearer's ear. The present invention further relates to an external device handling a speech stream intended for the hearing aid, and how to improve speech intelligibility of the audio signal. The invention also relates to a method of improving speech intelligibility of an audio signal.
2. The Prior Art
Modern, digital hearing aids comprise sophisticated and complex signal processing units for processing and amplifying sound according to a prescription aimed at alleviating a hearing loss for a hearing impaired individual. Furthermore, connectivity is an important issue for modern digital hearing aids. Advanced hearing aids may have means for interconnection which offers the advantages that timing and relative signal strength of an audio signal received by the microphones provides valuable information about the audio signal source. Furthermore, hearing aids have been able to receive telecoil signals for many years, and this technology has been regulated by the ITU-T Recommendation P.370. Several hearing aid manufacturers have developed each their own proprietary wireless communication standard with external devices for wireless streaming of audio signals in an electromagnetic carrier from e.g. a television via the external device.
Hearing aids have commonly been stand-alone devices, where the main purpose has been to amplify the surrounding sound for the user. However, there has been a significant development within smartphones and Internet access via these smartphones. Recently, the Bluetooth Core Specification version 4.0—also known as Bluetooth Low Energy—has been adopted, and since then, there has been developed various chipsets having a size and a power consumption falling within the capabilities of hearing aids, whereby it has become possible to connect a hearing aid to the Internet and get the benefit from such a connection.